Title molded trays with means to prevent jamming

ABSTRACT

A tray in the shape of a plate manufactured from fiber pulp or a similar material, particularly an egg tray is provided with means for preventing the walls of recessed portions from being jammed one on the other when stacking the plates. Between a number of recessed portions, a number of ridges or dams, disposed higher than the dams or ridges between the other recessed portions are provided. The higher dams or ridges are so distributed all over the plate surface and according to such a pattern that mutually equally designed plates, only when turned at an angle of 180*, can be so placed one on top of the other that then only the higher ridges or dams serve as supports between two successive plates.

United States Patent 1 de Vries [4 1March 13, 1973 1 TITLE MOLDED TRAYSWITH MEANS TO PREVENT JAMMING [75] Inventor: Marcus de Vries,Leeuwarden,

Netherlands [73] Assignee: N. V. Leeuwarder Papierwarenfahriek,Leeuwarden, Netherlands [22] Filed: Oct. 26, 1970 [21] Appl. No.: 84,190

7 Related US. Application Data [63] Continuation of Ser. No. 795,000,Jan. 29, 1969.

[52] US. Cl ..217/26.5

51 Int. l ..B65d 81/ 16, 865d 85/32 [58] Field of Search ..2l7/26.5, 26

[56] References Cited- UNITED STATES PATENTS 7 2,997,196 8/1961 Emery3,120,901 2/1964 Boyd.....-. 3,282,458 11/1966 Rudd .,..217/26.5

2,078,927 5/1937 Dorr ..2|7/26.5

Primary Examine rLeonard Summer AttorneyWenderoth, Lind & Ponack [57]ABSTRACT A tray in the shape of a plate manufactured from fiber pulp ora similar material, particularly an egg tray is provided with means forpreventing the walls of recessed portions from being jammed one on theother when stacking the plates. Between a number of recessed portions, anumber of ridges or dams, disposed higher than the dams or ridgesbetween the other recessed portions are provided. The higher dams orridges are so distributed all over the plate surface and according tosuch a pattern that mutually equallyv designed plates, only when turnedat an angle of 180, can be so placed one on top of the other that thenonly the higher ridges or dams serve as supports between two successiveplates.

1 Claim, 3 Drawing Figures PATENTEnmlslsza 3,720,344

sum 10F 2 'gV a V 4%): A it lli lOulliugmllu MARCUS de VRIES, v

INVENTOR ATTORNEY 1. TITLE MOLDED TRAYS WITH MEANS TO PREVENT JAMMINGThis application is a continuation of U.S. Pat. application Ser. No.795,000, filed Jan. 29, 1969.

From practice plates molded from fiber pulp are generally known, suchplates being formed with mutually spaced conical or somewhat coneorpyramidshaped cavities, the latter separatedone from the other byequally conical and/or somewhat'coneorpyramidshaped embossments. Theseplates or trays are generally known as so-called egg-trays and theyserve for shipping and stoling' a great number of eggs, whereas the eggsare protected then against mutual contact and in consequence thereofagainst possible damage by the above mentioned embossments.

The material from which these egg-trays are made, is very light andtherefore in this respect does not cause any difficulty in thetransportation of the empty material. On account of their shape thetrays re relatively voluminous which does create transportationproblems. However, in practicethe empty trays may be piled one on top ofand partially into the other and in.

doing so the hollow embossments on the lower side of piled up plates ortrays alternately receive the embossmerits of an underlying equablydesigned plate.

However, the fact that the embossments are conical or correspondinglyshaped, forms a serious practical difficulty since then the embossmentswill jam one in the other arid it will not be possible to easily takethe trays separately, from a pile.

The mentioned difficulty has already been known, and various proposalshave been made for preventing the cup-shaped parts of the plates fromengaging too deeply with one another and from their subsequent mutuallyjamming. It is known to form a small massive block or cam in somecorners of the tray which block or cam serves as a stopping cam andshould prevent the cups from telescoping too far. It is well known toprovide ridges in the trays with vertical walls of such a narrow shape,that during the molding of the trays they are saturated with pulp mass.As the trays are piled up the so formed massive ridges will be disposedone on the other and they also ke'ep the cups separated from each other."A serious disadvantage connected with the manufacture is attended withthese known processes. In consequence of the narrow limitations of theridges or cams, locations are formed in the suction mold, by means ofwhich the plates are molded from fiber pulp, where the fiber mass hassome difficulty in releasing ,itself from the mold. Then, as after themolding the molded plate has to be transferred to the usual transitionalmold, the fiber mass will remain in the primary or suction mold and thelatter will be clogged. This will lead to'irregularly shaped products.

The present invention has as its object the provision of atray-construction which enables the trays to be piled up closelytogether whereas nevertheless the risk of mutually jamming is prevented.A further objectof the invention is to make the necessary provisions forthat purpose without any harmful influence upon the' manufacturingprocess. .Such provisions, make it possible to maintain practicallyequal wall thicknesses throughout the trays,- and in consequencethereofprevent the risk of clogging up the primarysuction molds.

' remaining absolutely free of one another.

According to the invention, these objects are achieved by the provisionof a plate of the type mentioned which has formed thereon a number ofdamsor ridges between a number of recessed portions. The dams or ridgesare disposed at a higher level than the dams or ridges between otherrecessed portions. The said elevated dams or ridges are distributed overthe plate surface asymmetrically according to such a pattern thatmutually equally designed plates, when mutually turned at an angle of l,can be stacked one on top of the other, that then only the elevated damsor ridges of the lower plate contact with the next upper plate.

It is obvious that for realizing this possibility the pattern inquestion may be designed in many different ways.

In order to prevent the walls of the cups, which walls are generallyrather rough and offer a great frictional resistance, from contactingone another, turning the plates mutually atan angle of is a requirement,this with a view to the uniformity in manufacturing of the plates beingstacked. This however is the manufacturers concern who has to see to thetransportation of the plates, and the manufacturer can easily take thenecessary measuresfor proper stacking of the plates. Then the user hasthe great advantage of easily releasing the plates one from the other.

' Now the invention will be explained with the help of the accompanyingdrawings which illustrate one er'nbodiment-of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a tray inaccordance with the present invention;

FIG. 2 is a cross-sectional illustration taken along line II-II in FIG.1; and

FIG. 3 is a cross-sectional illustration taken along line III-III inFIG. 1.

The figures show a tray according to the invention. The trays arerepresented in the usual way with the embossments 1 separating recesses2 turned upwards. Between these embossments the normal dams 3 having afirst height are disposed. According to the invention, higher dams 4 arealso provided and which have a more narrow face, since the faces 5 and 6thereof taper further upwardly. At the points indicated shadedly theelevated dams 4 are disposed asymmetrically according to such a patternthat similar plates, when at an angle of 180, are so disposed one on theother that the elevated dams 4 or the lower tray contact only the normaldams 3 of the next upper plate or tray.

IF apattern is chosen wherein in a row a dam is alternately higher withrespect to its adjacent darn, it will be clear that all dams of twosuccessive plates will rest one uponthe other. In case a differentpattern is applied and e.g. in a row a number of dams remain at the samelevel, it will be necessary in turning at an angle of 180 to have thehigher dams face the deeper recesses which have resulted from disposingthe higher dams in the other plate. So'a number of plates are capable ofI claim:

1. In a set of rectangular molded pulp trays, particularly for use inpacking objects such as eggs, wherein each of said trays has an upperobject-receiving surface comprising a plurality of parallel rows ofraised emsecond plurality of said dams extending upwardly bossments, aplurality of parallel rows of object-receivwith respect to said surfaceof a second height ing recesses, said rows of recesses being alternatelyargreater than said first height in alignment with said ranged betweensaid rows of embossments, said emfirst plurality of dams in said rows,said second plubossments being joined by and said recesses being 5rality of dams being positioned so that the pattern separated byintegrally molded d m ar n ed i rows thereof on said surface of saidtray is asymmetrical parallel to an edge of said tray and having meansfor with respect to a center line of said y such that preventing thewalls of said embossments and said when a first f 531d yis rotated andrecesses from b i jammed when said rays are stacked on a second of saidtrays, said first pluralistacked one upon h other; ty of dams of saidfirst tray aligns with and rests on the improvement wherein said meanscomprises a only Second plurality of dams Said Second first plurality ofsaid dams extending upwardly with respect to said surface for a firstheight, and a

1. In a set of rectangular molded pulp trays, particularly for use inpacking objects such as eggs, wherein each of said trays has an upperobject-receiving surface comprising a plurality of parallel rows ofraised embossments, a plurality of parallel rows of object-receivingrecesses, said rows of recesses being alternately arranged between saidrows of embossments, said embossments being joined by and said recessesbeing separated by integrally molded dams arranged in rows parallel toan edge of said tray and having means for preventing the walls of saidembossments and said recesses from being jammed when said trays arestacked one upon the other: the improvement wherein said means comprisesa first plurality of said dams extending upwardly with respect to saidsurface for a first height, and a second plurality of said damsextending upwardly with respect to said surface of a second heightgreater than said first height in alignment with said first plurality ofdams in said rows, said second plurality of dams being positioned sothat the pattern thereof on said surface of said tray is asymmetricalwith respect to a center line of said tray such that when a first ofsaid trays is rotated 180* and stacked on a second of said trays, saidfirst plurality of dams of said first tray aligns with and rests on onlysaid second plurality of dams on said second tray.